In recent years, there has been proposed a system in which AV (Audio Video) equipments such as CD (Compact Disc) player or digital video, etc. is connected through network to transmit or receive audio stream or video stream. As network for realizing such a system, there is, e.g., network in which AV equipments are connected by serial bus in conformity with the IEEE 1394 where various standards are drafted with IEEE Std. 1394-1995: IEEE Standard for a High Performance serial Bus recognized by IEEE (Institute of Electrical and Electronics Engineers) being as the fundamental specification.
In the IEEE 1394, AV/C (Audio Video/Control) command is employed as command set in protocol in which content relating to control of AV equipment is defined. In addition, in the IEEE 1394, setup in transmission of AV signal and transmission packet format are prescribed in IEC (International Electrotecchnical Commission) 61883, and management of logical connection and disconnection between equipments is carried out in conformity with connection management in accordance with this IEC 61883.
In such IEEE 1394, with respect to flow of stream within the equipment, Plug Control Register (hereinafter abbreviated as PCR) defined in the IEC 61883 is used to carry out management of logical input/output port for carrying out input/output of data. On the other hand, in the IEEE 1394, with respect to flow of stream between different equipments, AV/C serial bus plug defined in the AV/C command is used to carry out management of logical input/output port for carrying out input/output of data. Further, in the IEEE 1394, these PCR and AV/C serial bus plug are caused to have one-to-one correspondence. For this reason, in the IEEE 1394, connection is established, e.g., between plug of subunit serving as source of data and plug of unit so as to have one-to-one correspondence, and correspondence between flow of stream within the equipment and flow of stream between equipments becomes clear. Accordingly, control of the entirety of the system is facilitated.
Meanwhile, in recent years, as one technology of short range wireless communication standard which has been developed in order to mutually carry out wireless connection of portable terminal machine and peripheral equipment thereof, attention is drawn to Bluetooth™ Wireless Technology. Further, in recent years, there has been tried a method in which Bluetooth Wireless Technology is applied to AV equipment to carry out wireless communication of audio stream or video stream.
In such Bluetooth specification, two protocols, i.e., protocol called AVCTP (AV Control Transport Protocol) and protocol called AVDTP (AV Distribution Transport Protocol) are prescribed The AVCTP is protocol in the Bluetooth in which content relating to control of AV equipment is defined, and the above-described AV/C command is employed similarly to the IEEE 1394 as command set in the AVCTP. On the other hand, the AVDTP is protocol in the Bluetooth specification in which content relating to transmission of AV signal is defined, and is protocol corresponding to connection management in accordance with the above-described IEC 61883.
These AVCTP and AVDTP are protocols independent each other. For this reason, in the Bluetooth application, in such cases that, e.g., transmission of AV signal is not carried out, but operation control of AV equipment is carried out merely by remote control, if only AVCTP is used, it is possible to control the AV equipment. On the other hand, in such cases that the AV equipment is not controlled, but transmission of AV signal is merely carried out, if only AVDTP is used, it is possible to carry out transmission of AV signal.
However, in the Bluetooth specification, there is no relevance between interface with respect to stream within the equipment which is defined at the side of AVCTP and interface with respect to stream between equipments which is defined at the side of AVDTP.
For this reason, in the Bluetooth application, even if, e.g., audio stream or video stream can be received, equipment of that receiving side could not recognize signal source of stream. In more practical sense, in the case where equipment of the transmitting side of stream employs plural subunits as signal source, when, e.g., equipment of the transmitting side has two signal sources of player and tuner, the equipment of the receiving side could receive stream from these respective signal sources, but could not recognize that received stream is outputted from any signal source. Accordingly, the equipment of the receiving side could not notify information of signal source to user by display, etc. As described above, the system to which Bluetooth specification is applied could not carry out control of the entirety of this system. As a result, convenience was injured for user.
In addition, in the Bluetooth specification, procedure when connection is given is prescribed between equipment of the transmitting side and equipment of the receiving side by AVDTP. Accordingly, in the Bluetooth specification, while control could be carried out in connection with mutual connection by these two equipments, it was impossible that the third equipment except for the two equipments is caused to be controller to control connection between these two equipments.